Logging

FastSchema provides a built-in logging system that can be used to log useful information about the application.

zaplogger is a package that implements the logger.Logger interface and is built on top of the Uber Zap package, which is a high-performance logging library.

Example Output:

{
  "level": "info",
  "ts": "2024-05-30T09:43:19.894050754+07:00",
  "caller": "restfulresolver/middlewares.go:58",
  "msg": "Request completed",
  "request_id": "0007d2f7-a767-43cf-ae48-9b2f9d3c099f",
  "params": [
    {
      "ip": "127.0.0.1",
      "latency": "0s",
      "method": "GET",
      "path": "/api/hello",
      "status": 200
    }
  ]
}

A log line consists of the following fields:

• level: The log level.
• ts: The timestamp of the log.
• caller: The file and line number where the log was called.
• msg: The log message.
• request_id: The request id of the incoming request if available.
• params: Additional parameters that are logged with the message.

Logger Interface

type Logger interface {
	Info(...any)
	Infof(string, ...any)
	Error(...any)
	Errorf(string, ...any)
	Debug(...any)
	Fatal(...any)
	Warn(...any)
	Panic(...any)
	DPanic(...any)
	WithContext(context LogContext, callerSkips ...int) Logger
}

Configuration

FastSchema logger supports logging to both the console and a log file. You can configure the logger by providing a logger.Config object to the NewZapLogger function.

type Config struct {
	Development    bool `json:"development"`
	LogFile        string
	CallerSkip     int
	DisableConsole bool
}

• Development: Whether to run the logger in development mode.
• LogFile: The path to the log file.
• CallerSkip: The number of stack frames to skip when logging.
• DisableConsole: Whether to disable console logging.

Usage

FastSchema does not provide a global logger instance. Instead, you have to get the logger instance by using one of the following methods:

Using app.Logger():

This method returns the logger instance for the application.

app, _ := fastschema.New(&fs.Config{
  SystemSchemas: []any{Tag{}, Blog{}},
})

app.Logger().Info("Hello, World!")

Using fs.Context.Logger():

This method returns the logger instance for the current request context.

FastSchema assign a request id to every incoming request, this request id is useful for tracking logs related to a specific request.

When you use fs.Context.Logger(), the logger will automatically include the request id in the log message, it is a good practice to use this method to log information in every resource handler.

app, _ := fastschema.New(&fs.Config{
  SystemSchemas: []any{Tag{}, Blog{}},
})

app.API().Add(fs.Get("hello", func(ctx fs.Context, _ any) (any, error) {
	ctx.Logger().Info("Hello, World!")
  return "Hello World", nil
}, &fs.Meta{Public: true}))

app.Start()

Example Output:

Console

2024-05-30T09:42:06.142592425+07:00	info	cmd/main.go:56	Hello, World!	{"request_id": "b3af6b86-ac69-491f-a82e-6f658dd9a315"}
2024-05-30T09:42:06.142723638+07:00	info	restfulresolver/middlewares.go:58	Request completed	{"request_id": "b3af6b86-ac69-491f-a82e-6f658dd9a315", "params": [{"ip":"127.0.0.1","latency":"0s","method":"GET","path":"/api/hello","status":200}]}

Log file

{"level":"info","ts":"2024-05-30T09:43:19.89399056+07:00","caller":"cmd/main.go:56","msg":"Hello, World!","request_id":"0007d2f7-a767-43cf-ae48-9b2f9d3c099f"}
{"level":"info","ts":"2024-05-30T09:43:19.894050754+07:00","caller":"restfulresolver/middlewares.go:58","msg":"Request completed","request_id":"0007d2f7-a767-43cf-ae48-9b2f9d3c099f","params":[{"ip":"127.0.0.1","latency":"0s","method":"GET","path":"/api/hello","status":200}]}

Custom log context

A log context is a map of key-value pairs that can be used to add additional information to the log message.

ctx.Logger().WithContext(logger.LogContext{
	"key1": "value1",
	"key2": "value2",
}).Info("Hello, World!")

This will output the following log message:

{
  "level": "info",
  "ts": "2024-05-30T09:50:25.586195304+07:00",
  "caller": "cmd/main.go:60",
  "msg": "Hello, World!",
  "key1": "value1",
  "key2": "value2"
}

Caller Skips

The CallerSkip field in the logger.Config struct is used to skip a number of stack frames when logging. This is useful when you want to skip the logging of the logger's internal functions or unnecessary stack frames.

CallerSkip can be set at the application level or at the logger level.

Application level

app, _ := fastschema.New(&fs.Config{
	SystemSchemas: []any{Tag{}, Blog{}},
	LoggerConfig: &logger.Config{
		CallerSkip: 1,
	},
})

Logger level

ctx.Logger().WithContext(logger.LogContext{}, 1).Info("Hello, World!")